Telephone system.



PATENTED JAN. 15, 1907.

W. W. DEAN. TELEPHONE SYSTEM. APPLIOATIONIILED JAN. 23. 1904,

2 SHEETS-SHEET PATENTED JAN. 15, 1907.

W. W. DEAN. TELEPHONE SYSTEM. APPLICATION FILED JAN. 23, 1904.

2 SHEETSSHEET 1 instead of being normally UNITED WILLIAM W. DEAN, OF

SWITCIIBOARD AND' SUPPLY CORPORATION OF ILLINOIS.

I PATET FIOE.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 15, 1907.

An licationfi January 23,1904. Serial No 190,311.

To all whom, it inn/ 1 concern.-

Be it known that I, VVI LLIAM W. DEAN, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented a new and useful Improvement in Telephone Systems, of which the following is a specification.

My invention relates to improvements in telephone systems, and particularly to systems in which the subscribers lines are of the two-wire type. In the systems of this type heretofore it has been common to provide the lines at the central ofiice with linerelays which are adapted to be operated when a subscriber takes up his receiver to close the local circuit of the line-signal to operate the same. A second relay,fknown as the switching or cut-oiI relay, is also commonly provided for each line and is 0perated when the operator connects her cordcircuit with the telephone-line and serves when so operated to disconnect the said linerelay to thereby retire or prevent the operation of the line-signal.

In this invention the lines are provided, as usual, with line-signals and with line and cut-off relays to suitably but the line-relays are preferably permanently connected with the telephone-line and are not disconnected during conversation. One .side of the telephone-line may thus be permanently extended through the corresponding contacts of the spring-jacks disconnected, as in some prior systems. A cord-circuit having suitable supervisory apparatus associated' therewith may be used to establish connections for conversation, an operators telephone set and ringing-generator being arranged to be readily connected with such circuit.

The invention is illustrated in the acc'bmpanying drawings, in which,

Figure 1 is a diagram representing telephone systems embodying my improvements, and Fig. 2 is a similar View of a somewhat-different arrangement.

Like reference characters indicate like parts in both views.

Referring to Fig. 1, L and L indicate two subscribers lines extending in two limbs 2 and 3 from their respective substations to the central ofiice, where they are control the signals;

us'ual line-signals S, normally controlled by the line-relays R, permanently connected between the line conductors 2 and ground. The line appurtenances include in addition the usual answering-jack J and a plurality of multiple jacks, such as J and J, in any desired number, suitably distributed throughout the multiple board, the tip-contacts of said jacks being permanently connected with the line conductor 2, while the sleeve-contacts are normally disconnected from lineconductor 3, but are adapted during connections for conversations to be united there' with by means of the cut-ofi relay R whose winding is legged to ground from the sleeveconductor of said jacks and which controls normally closed contacts in the circuit of the signal S. The line conductor 3 is normally connected,through a spring of said relay R, with the conductorfl; omnibus-bar 5, leading from the live pole of the central or common battery B. At the substations each'subscriber is provided with a call-bell 6 and a condenser 7 in a bridge of the line conductors that is normally closed by the switch-hook 8; but when the receiver 9 is lifted from said switch-hook for conversation the bridge of the. bell is opened and the transmitter 10, retardation-coil 11, together with the condenser 7 and receiver 9, are suitably connected" in circuit. This substation apparatus; is intended merely to typify any outfit.- At the c ntral ofIice each operator is provided with a plurality of cord-circuits of the type shown in the drawings, each cordcircuit being provided with an answering-plug P and a calling-plug P having tip-and-sleeve contacts adapted to register with the corresponding contacts of the spring-jacks when inserted therein. The tip-contacts of these plugs are united through the medium of flexible strands t and t and the interposed condenser c, joined by the similar strands s and s and the interposed condenser 0 The supervisory relays 1" and r are included in a bridge of the answering end of the'cord-circuit upon opposite sides of the said battery B and together control the local circuit of the supervisory signal S which is associated with the answering-plug P, and preferably consists oi a fitted with the 1 small incandescent lamp. A second pair of while their sleeve-contacts are branching from the 1 usual desired common-battery 7 supervisory relays r and r are similarly connected across the calling enzl of the cord-circuit, together with the battery B and like- Wise control the local circuit of the supervisory signal S that' is assigned to the plug P The operators set, including her head-recelver 12, the secondary of her induction.-

said key simultaneously connects the sleeve side of the cord-circuit with the ,live pole of the battery B by means of conductors 1'7 and 5 In the operation of the system shown in this figure the subscriberupon the line L, for exampletakes up his receiver, thereby completing a path for current from the battery B over conductors 5, 4, and 3, thence through the substation devices and backto the central office overthe line conductor 2 and through the line-relay R to ground. The current in this path suffices to actuate the said line-relay, with the result that the local circuit of the si nal S is closed at its forward contacts, and tiie lamp is thus lighted to indicate the subscribers call.

pon observing the signal the operator inserts the answering-plug P of her cord-circuit in the answering-jack and de resses her listenin -key to connect her set wlth the cord-circuit, to bethereby put in communication with the calling subscriber. The ins'ertion of the plug P,in' the first place, closes a path for current from the live pole of the battery B through supervisory relay r sleeve-strand s of the cord-circuit, andthe sleeve-conductor of the jack-section of the line, and thence through the winding of the cut-off relay R to ground. The cut-ofl relay is thus actuated and serves circuit of the line-signal S to automatically retire the same and also to disconnect the line conductor 3 from the branch 4 and connect itwith the. sleeve-conductor of the to open the local acks to thus place the line in condition for The simultaneous actuation of the supervisory relay r closes the local circuit of the supervisory signal S"; but the instant the line conductor 3 is connected with the jack-section of the line, current from the battery B is permitted to circulate in'the metallic circuit of the telephone-line, owing to the fact that the subscribers telephone is now off its hook, and the supervisory relay is thus actuated to open the local circuit of said signal S which is accordingly prevented from operating. Upon learning the order of conversation.

'sistance.

dicating that the line id idle, while a click in her receiver indicates that the line is' busy. Assuming that the line is found idle, the calling-plug P is inserted in the said multiple jack of'the line L and the ringing-key 16 is depressed. During the operation of the ringingkey the cut-off relay R of this line is maintained actuated by current from the battery B flowing over conductors 5 and.

17 and through said cut-oil relay to ground.

The ringing-current is sent out over the tip side of the telephone-line through the condenser and call-bell at the substation, with return over the sleeve side of the telephoneline and through said conductors 17 and 5 and the battery B to ground. After the subscriber has been called, but before his response, the battery B is furnishing current over the sleeve strand 8, to maintain said eutoil' relay operated, and at the same time the supervisory relay 7" is actuated by the current in this path, and the local circuit of the supervisory signal S is accordingly closed to'light the said signal, which indi- .catesto the operator that the called subscriber has not yet responded. Upon his response it is apparent that current from the battery B circulates in the metallic telephone-line, thereby furnishing'current to the subscribers transmitter and at the same time operating the supervisory relay 1"" to open the local'circuit nal S which is retired, thus indicating to the operator that the subscribers-are in communication. During conversation the batteries B and B 'are independently supplying current to the substations for the operation of the transmitters and for the operation of the various relays at the central office. For instance, tracing the flow of current from the live pole of the battery B it will be seen that the winding of the eut-ofl relay R? is included in a local circuit with said source. and that the line-circuit is in parallel therewith. In

the return of the current sent out over the line a portion flows throughthe permanently-connected line-relay R, while the remainder passes through the su ervisory relay 1. Good results have been 0 tained with this type of line-circuit with the cutpfl'relays of five hundred ohms resistance and the line-relays likewise of live hundred ohms re- The supervisory relays in the cordcircuit may be of the usual dimensions. At the termination of the conversation the re turn of the receivers to theirhooks opens the line-circuits and deenergizes "the supervisory of the supervisory sigrelays r and 1- but since the cooperating relays r and r are maintained actuated through the local circuits and are independent of the subscribers the signals S and S are lighted. Upon observing these signalsthe operator takes down the connection and restores all parts to normal condition.

In Fig. 2 the substation apparatus upon the lines L and L are the same. The linec-irc'uit is likewise the same as in Fig. 1 except that the line-relay R has preferably a resistance of about two hundred ohms and is connected between the line conductor 2 and the live pole of the central common battery B, while the opposite line conductor is connected with the ground. As before; the line-relay controls normally open contacts in the circuit of the line-signal, while the cut-oil relay R controls'normally closed contacts of said circuit. The cord-circuit in this instance is provided with a pair of supervisory relays 1' and 1*, bridged across the answering end, with the middle point of their bridge joined by a conductor with the live pole of the battery B, these relays controlling the local circuit of the supervisory signal S Similarly, a second pair of supervisory relays r and 7" are bridged across the calling endiof the cord-circuit, and the middle point of said bridge is joined by conductor 21 pole of the second battery 3. In this instance also the supervisory relay 1' is provided with an additional contact 22, connected with'the tip-contact. of the callingplug P which normally is connected, by means of a branch 23, with an additional spring 24 upon the listening-key 25. By means of said additional spring 24 a suitable high-impedance and high-resistance test-relay 26 is connected with said conductor 23 when the listening-key is operated. The operators head-receiver 12, the secondary of her induction-coil 27, and the condenser c may be bridged across the callingend of the cord-circuit by means of the listening-key springs 25, while her transmitterhi and the primary of her induction-coil 27 may be charged from either the battery B or B A tertiarywinding of said induction-coil is connected between the lead 5 and the forward contact of said testrelay 1'". The ringinggenerator is the sameas in the prior figure and need not be specifically described. The cut-off relays may be of two hundred ohms resistance. In the operation of the system the' subscriber upon the line L takes upv his receiver, thereby completing a circuit through the line-relay R which is energized to close the local circuit of the linesignal S. Upon observing this signal the operator inserts the answering plug I of her cord-circuit, thereby completing a path for current from the live pole of the battery B, through the conductor '20, supervisory relay 1', sleeve-strand s of the cord-circuit, sleeve-conductor of the jack- With, the live 1 section of the telephone-line, and through .the cut-off relay R to ground. The current in this path actuates the cut-off relay and causes it to open the'line-sign'al circuit to retire the same and also to disconnect the line conductor 3 from the branch conductor 4 and to bring it into engagement vvith the sleeve- -.contacts of the jacks. Owing to the fact that the subscribers telephone is ofi' its hook, current from the live pole of the battery B now also flows through the winding of the line-relay R as well as through conductor 20, 'the tip supervisory relay T the tip-conductor of the jack-section of the line, and thence'from both these paths'out over the tip line conductor 2 to the substation, with return through said sleeve-conductor 3 of the telephone-line and the winding the cut-oft relay 1? to ground. Thus the supervisory signal S is prevented from now 0 erating. pon learning the order of the cal ing subscriber the wanted line is tested in the usual manner, the application of the tip of the calling plugto the test-ring of a busy line result- 26, thereby causing a click in the operators receiver. If the line is found idle, however, no 0 ick 's received and the balling-plug P is inserted in one of the multiple jacks of the line. The depression of theiringing-key calls the wanted subscriber in the usual manner, and after being called the supervisor 1' is actuated to disconnect the test-re ay and to place the cord circuit in condition for conversation, as well as to close the local circuit of the supervisory signal S, which is lighted. The response of the called subscriber permits the excitation of the relay rkwhich retires the supervisory signal and indicates to the operator that the parties are in conversation. During conversation the batteries B and B are feeding current to the respective lines mainly through the line and cut-off relays. At the termination of the conversation the return of the subscribers receivers to their hooks deenergizes the tip'supervisory relays r and r and causes the lighting of the corresponding supervisory signals, upon seeing which the operator withdrawsthe plugs and restores all parts to normal condition. The supervisory relays in this instance preferably are of about five hundred ohms resistance lines for conversation mainly through the line and cut-ofl relays. The line-relays are phone-lines and do not require disconnection during conversations. The tip line conductors may be extended directly to the tips of the jacks, and other advantages are apparent.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is y 1. In a telephone system, tion with a telephone-line, of a line-relay for ing in afiow of current through the test-relayrelay IQO each, since the current is fed to the telephonethus permanently connected with the tele- Y the combinasaid line, one terminal of the coil of said re lay being connected to one limb of the line and to one contact of the line-jack, the other terminal of said relay-coil'being connected to one pole of a central battery, a line-signal, a single pair of normally open contacts for 1 said relay adapted to close the circuit of said signal, acut-off relay having one terminal of its Winding connected to'the same side of the central battery with which the line-relay connects, and having its other terminal connected'with the other contact of said linejack and with a normally open contact of said cut-off relay, a pair of normally closed contacts for said cut-off relay adapted byv their actuation to open the circuit of the line-' signal, a movable *cont act of said relayada ted normally to connect one limb of said line directly to one side of the central source but in its actuated position to connect said limb to said normally open contact of the cut-offrelay, substantially as described.

2. In a telephone system, the combination with a telephone-line, of a line-signal there-' for, a line-relay ermanently c nnected with the tip side of t e line and controlling normally open contacts in the circuit of said signal, a cut-off relay for the line legge'd to ground from the normally disconnected sleeve-contacts of the jacks, said cut-off relay serving when operated to open thecir .same, substantially as described.

nected with one 'pole cuit of said signal and to sever the normal connection of the sleeve side of the line and complete the connection between said sleeve side of the line and the jack-section of the 3. In a telephone system, the combination with a telephone-line, of a cord-circuit to establish connections therewith for conversation, a line-relay and a line-signal the tip connection of said sleeve line conductor and 1 connected with the said; test-contacts and also to open the circuit of said signal, substantially as described. A 1

Signed by me at Chicago, county. of Cook, State of Illinois, this 31st day of December.

. WILLIAM W. DEAN. Witnesses: I

E.'A.' GARLOCK, ROBERT LEWIS Arms. 

